In the related art, in a chair used in a room, a seat in a vehicle, or the like, a cushion material or a soft pad is frequently used in a portion to be touched by a human body, such as a seat surface or a back rest, and the surface thereof is covered with a cover material. Various structures are employed for fastening such a cover material. As a structure capable of fastening the cover material and visually being concealed, there has been known a structure in which a wire is disposed in a groove of the cushion material, clips are arranged at predetermined positions of an edge of the cover material, and the clips are engaged with the wire to fasten the cover material.
For example, cover material fastening clips disclosed in Patent Document 1 and Patent Document 2 include a chuck portion that is hooked to a locking end portion attached to a cover material and a hook portion that is hooked and locked to a wire disposed in a groove of a cushion material. The hook portion includes a guide piece and a hook piece which are disposed to face each other in parallel, the guide piece is bent outward to enlarge a gap between the hook piece and the guide piece by inserting the wire therebetween, and the hook piece is hooked and locked to the wired inserted into the gap when the wire is further inserted.
As a structure in which a hook is hooked to a wire to fasten a cover material, there has been known a hook member disclosed in Patent Document 3. In this structure, a cantilever-shaped closing piece capable of being elastically deformed is disposed in an opening formed on the top of the hook. As disclosed in Patent Document 4, there has been suggested a structure in which a hook having a pair of locking claws having the same shape is disposed on both sides of a hanging member attached to a cover material.
Patent Document 1: Japanese Patent Application Publication No. 2012-235911A
Patent Document 2: PCT Publication No. WO2012/017986
Patent Document 3: U.S. Pat. No. 4,691,416
Patent Document 4: Japanese Utility Model Application Publication No. H7-16659A
In the cover material fastening clips disclosed in Patent Document 1 and Patent Document 2 in the related art, since the guide piece extends long, it is difficult to engage with the wire. That is, when the cover material fastening clip in a tilted state approach the wire, the guide piece and the hook piece extend downward to be close to each other. Accordingly, the wire is located outside the guide piece and thus the wire may not be hooked to the hook piece. In this case, the posture of the hook piece needs to be changed and the hook piece needs to be inserted again, thereby making an operation of locking the hook piece troublesome. In addition, since the range in which the wire can be inserted into the hook piece is narrow, the surrounding cushion material or the like needs to be stretched and deformed to make the wire appear for the purpose of accurate insertion. Accordingly, workability was poor and the operation was not easy. Particularly, when the cover material fastening clip is pressed and hooked to the wire with a finger, the cover material fastening clip is likely to be inclined such that the guide piece is located downside and the wire is likely to be located outside the guide piece. Accordingly, it is difficult to engage the wire with the hook piece.
In the hook member disclosed in Patent Document 3, since the locking opening is formed in the top of the hook, the hook has to be pressed up to below the wire so as to lock and unlock the wire. Accordingly, a large force is required and it is difficult to use the hook member. In addition, the opening is closed with the closing piece. Accordingly, when the hook member is removed from the wire, the operation has to be carried out while holding the closing piece in an opened state and thus it is difficult to carry out the operation.
In the locking claws disclosed in Patent Document 4, similarly to the hook member disclosed in Patent Document 3, since the locking opening is formed in the top of the hook, the wire is locked by pressing the hook up to below the wire and then raising the hook. However, since it is difficult to see the position of the wire, it is difficult to engage the wire with the hook.